According to a conventional stencil printing device, a heat-sensitive stencil master plate sheet is paid off from a roll, and is thermally perforated into images to be printed. The thus perforated master plate sheet is conveyed to a printing drum, and is mounted around the outer circumferential surface of the printing drum by rotating the printing drum with the leading edge of the stencil master plate sheet clamped to the outer circumferential surface of the printing drum. When a prescribed length of the stencil master plate sheet is mounted on the printing drum, it is cut by a master plate cutter placed in a path for conveying the stencil master plate sheet to the printing drum. An example of a stencil printing device incorporated with such a feature is disclosed in Japanese utility model publication (kokoku) No. 4-18867.
According to such a stencil printing device, because the master plate cutting device is placed in an intermediate point of the path for conveying the stencil master plate sheet to the printing drum, the length of the path must be increased due to the presence of the master plate cutter. This obviously is undesirable in minimizing the size of the stencil printing device.
Furthermore, the conveying rollers for the stencil master plate sheet must be always in engagement with the stencil master plate sheet, but cannot be placed ahead or downstream of the cutter. Therefore, a substantial length of the leading edge of the stencil master plate sheet which was initially located upstream of the cutter must be pushed out and forwarded to the clamping position on the printing drum during the initial phase of mounting the stencil master plate 10 sheet on the printing drum, and this creates some difficulty in ensuring the process of mounting a stencil master plate sheet on the printing drum to be carried out successfully every time.
Additionally, depending on the timing of the actuation of the cutter in relation to the rotation of the printing drum, the length of the stencil master plate sheet mounted on the printing drum may fluctuate being either too long or too short as the case may be, and this fluctuation when excessive may cause some problem with the printing process.
If an attempt is made to cut the stencil master plate while the printing drum is rotating, the trailing edge of the cut stencil master plate sheet as well as the leading edge of the succeeding stencil master plate sheet may become slanted, and this causes some difficulty in properly clamping the leading edge of the stencil master plate sheet.